Electric drive mower with trailed auxiliary power source

ABSTRACT

Provided is an all-electric riding greens mower. The mower includes a frame which is supported for movement upon a plurality of ground engaging wheels and upon which are supported a modularly interchangeable power source and a plurality of reel lawn mowers. An electric motor provides driving torque to enable movement of the mower between and over golf course greens or other surfaces to be mowed, electric motors provide driving torque for each of the reel lawn mowers. The interchangeable power source provides electrical energy for driving the electric motors, including the primary mover and the electrical motors for the reel type lawn mowers. The modularly interchangeable power sources may comprise a bank of batteries, a motor/generator set, a fuel cell, or a combination of these. The power source may be easily exchanged in the field for another, freshly charged power source. Exchange occurs using either a fixed change stand or a mobile change stand. The change stands are configured to facilitate exchange by reducing friction caused by the generally weighty power source. The power source is delivered to the fixed stand on towable trailers.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a divisional of U.S. patent application Ser.No. 09/489,124 filed on Jan. 21, 2000 which claims the benefit of U.S.Provisional Patent Application No. 60/126,153 filed on Mar. 25, 1999.The disclosures of the above applications are incorporated herein byreference.

FIELD OF THE INVENTION

[0002] The present invention generally relates to electrically-poweredriding mowers for use on golf courses and other large grounds, and moreparticularly relates to electrically-powered riding mowers that utilizemodular, interchangeable electrical power sources which may include abank of batteries, a motor/generator set, a fuel cell or combinationthereof, for providing electrical power to the mower.

BACKGROUND OF THE INVENTION

[0003] The assignee of the present invention recently introduced anall-electric riding greens mower. The mower of this all-electric ridinggreens mower is described in detail in U.S. Pat. No. 5,406,778, issuedApr. 18, 1995, the disclosure of which is hereby incorporated byreference. The triplex riding mower disclosed in this patent has a bankof batteries supported near the rear of the frame of the riding mowerwhich provides electrical power for operating the main drive electricmotor, three reel motors, and three lift motors for raising and loweringthe reel type mowing heads as needed. The main motor drives a transaxlethat provides a driving force to the two forward wheels of the triplexmower. The three reel mowers each directly drive one of the reels, whichmay be operated independently. The three lift motors individually drivea screw-type lift mechanism which raises and lowers a head much the sameway that conventional hydraulically-powered single-rod cylinders do. Themower includes a foot pedal controlled by the operator which actuates apotentiometer which directs forward or reverse motion of the vehicle atany desired rate of speed, within the limits permitted by the drivemotor control circuitry and by the power capabilities of the main motorand batteries. Heavy duty contactors switchably apply electrical energyto the reel motors, which are provided with the full voltage of thebattery pack, which is nominally 48 volts presently obtained by eight6-volt batteries wired in series.

[0004] There are numerous advantages to using an all-electric ridinggreens mower. These include very quiet operation, because there is nonoisy internal combustion engine. Another advantage is the absence ofhydraulic devices and accompanying hydraulic oil on the machine, whicheliminates the possibility of hydraulic oil leaks. As is known,hydraulic oil leaks in conventional hydraulically-driven andhydraulically-powered turf care equipment can significantly damage agolf green or fairway if undetected by the mower operator.

[0005] Another major advantage of the all-electric greens mower is thatit does not produce byproducts of combustion, and thus can operate inareas where the use of conventional internal combustion powered mowersis prohibited due to pollution concerns and regulations.

[0006] While the disclosed all-electric greens mower is quitesatisfactory and much appreciated, it is difficult and impractical tomow large areas, such as fairways or parks with that style of mower,even when appropriate reel-style mowing heads are installed. The rangeof the battery packs carried by the present mowers remain inherentlylimited by the power capabilities of conventional batteries.

[0007] One challenge presently faced by many golf course operators isthat municipalities and communities, especially those which haveresidential homes bordering the golf courses, restrict by ordinance thehours during which the fairways and greens may be mowed. Homeowners havetired of noisy mowing equipment awakening them during the early morninghours, between 5:00 a.m. and 8:00 a.m., and disturbing them in theirleisure during the later evening hours, between 7:00 p.m. and 10:00p.m., when they expect peace and quiet in their neighborhoods. Golfcourse operators, on the other hand, dislike mowing their courses duringpeak golfing times, between 7:00 a.m. and 7:00 p.m. during the golfingseason. This challenge presents particular difficulties for golf courseowners whose courses are continuously busy, and usually have a waitinglist of people seeking tee times.

[0008] A sufficiently quiet mower, such as an all-electric mower wouldallow for mowing fairways and greens on golf courses even wherecommunities have instituted noise-limiting ordinances. This is becausethe all-electric mowers are very quiet. Unfortunately, the battery rangeof a riding electric mower with one bank of batteries (even though thebattery weight is in excess of 400 pounds) is limited. Battery-poweredcommercial mowers, therefore, remain impractical for mowing large areasdue to the typically extensive recharge times required to fully rechargethe battery and the undesirable need to interrupt the mowing process(which the golfers wish to have completed as expeditiously as possible)while the batteries are re-charging.

[0009] Therefore, it is a principal object of the present invention toprovide an electrically-powered riding mower which is capable of mowinglarge areas of turf, such as golf course fairways, soccer fields, parks,and municipal grounds. A related object is to provide an all-electricriding mower which is capable of mowing large areas while producing verylittle noise and minimizing mowing interruptions to replace or re-chargethe on-board power source.

[0010] Another object of the present invention is to provide anelectrically-operated riding mower that utilizes modular,interchangeable electric power sources which may include, for example, abank of batteries, a motor/generator set, or a fuel cell, individuallyor in combination, to provide electrical power to the mower. Stillanother object of the present invention is to provide removable,rechargeable electrical power sources on easily interchangeable trays,so that they can be quickly changed and moved about.

[0011] Yet another object of the present invention is to provide anadditional electrical power source in the form of a towed power sourcemounted on a trailer which provides supplemental electrical energy to anall-electric battery-powered mower so that it runs longer distances.

[0012] Yet another object is to provide a preferred method forefficiently utilizing such electrically-powered riding mowers havingtowed power sources.

[0013] Yet another object is to provide changing structures whichfacilitate the removal of replaceable, rechargeable electrical powersources from turf equipment, such as the disclosed fairway mowers.

[0014] Yet another object is to provide a stacked vertical power sourcechange rack, a horizontal power source change platform, and a towablepower source change platform.

[0015] Still further objects of the present invention are set forth inand will become apparent from the following summary of the invention andthe detailed description and claims thereafter.

SUMMARY OF THE INVENTION

[0016] In light of the foregoing problems and in order to fulfill one ormore of the foregoing objects, there is provided, in accordance with afirst aspect of the present invention, a self-propelled riding mowerhaving a frame supported on a plurality of ground engaging wheels. Theframe supports an electrical power source for supplying electricalenergy to the mower and further supports a plurality of reel type lawnmowers which are movable between a raised position and a loweredposition, in accordance with operation and non-operation, respectively.The reel mowers are driven by electrical motors which receive electricalpower from the power source, which may be, for example, a battery pack,a motor/generator set, or a fuel cell. A prime mover having an electricmotor is also supplied with electrical energy from the power source,where the prime mover is adapted to provide torque to one of the groundengaging wheels upon which the frame is supported.

[0017] There is provided in accordance with a second aspect of thepresent invention, a self-propelled riding mower having a framesupported on a plurality of wheels. A plurality of reel type lawn mowersare also supported by the frame and are movable between a raised,non-operative position and a lower operative position. The reel typelawn mowers are powered by electric motors which receive electricalpower from the power source. A prime mover having an electric motorsupplied with electrical energy from the power source provides drivingtorque for at least one of the ground engaging wheels. Further, theself-propelled riding mower includes support for at least a portion ofthe power source which engages and disengages the frame to enableremoval and installation of the power source.

[0018] In a third aspect of the present invention, a self-propelledriding mower having a frame supported on a plurality of ground engagingwheels. The mower also includes a first power source and a plurality ofreel type lawn mowers supported from the frame which are movable betweena raised position and a lowered position. The reel type lawn mowers aredriven by electric motors receiving electrical power from the powersource. Further, a prime mover comprising an electric motor suppliedwith electrical energy from the power source is adapted to providedriving torque to at least one of the ground engaging wheels. Furtheryet, a power source trailer is supported on a plurality of groundengaging wheels and supports a second power source. The trailerinterconnects with the frame by a hitch so that the self-propelled mowertows the trailer.

[0019] In accordance with another aspect of the present invention, apower source change stand for switching power sources between a vehiclehaving interchangeable power sources and an auxiliary power sourceplatform. The power source change stand includes a first support tosupport the power source on the change stand and a second support tosupport the power source on the change stand, one of which is empty. Tochange the power source, one of the two supports receives the depletedpower source from the mower, while other supports support a fresh powersource which is then placed on to the frame of the electrically poweredvehicle.

[0020] There is provided in accordance with yet another aspect of thepresent invention, a trailer for supplying electrical energy to aself-propelled riding mower including a frame for supporting a powersource and a pair of ground engaging wheels for supporting the frame.The trailer includes a tongue extending from the frame having a hitchfor interconnecting to the towing vehicle. The power source is theninterconnected to the towing vehicle in order to provide electricalenergy to the towing vehicle.

[0021] These and other objects, advantages and aspects of the presentinvention may be further understood by referring to the detaileddescription, accompanying Figures, and appended claims.

[0022] Further areas of applicability of the present invention willbecome apparent from the detailed description provided hereinafter. Itshould be understood that the detailed description and specificexamples, while indicating the preferred embodiment of the invention,are intended for purposes of illustration only and are not intended tolimit the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings form an integral part of the description of thepreferred embodiments and are to be read in conjunction therewith. Likereference numerals designate the same or similar components or featuresin the various figures, where:

[0024]FIG. 1 is a perspective view of a three-gang mower having areplaceable power source according to first aspect of the presentinvention;

[0025]FIG. 2 is a block diagram of electrical components of the mower ofFIG. 1, including a controller for directing the operation of thecomponents;

[0026]FIG. 3 is an exploded view of a replaceable battery pack and theroller platform on which the battery pack rests during operation;

[0027]FIGS. 4 through 6 are plan, perspective, and side views,respectively, of a power source change rack according to a first aspectof the present invention in which the power sources are movedhorizontally in order to be changed.

[0028]FIGS. 7 and 8 are side views showing a towable trailer forcarrying replaceable power sources for providing replacement to thechange rack of FIGS. 4 through 6;

[0029]FIGS. 9 and 10 show a towable trailer for providing replacementpower sources for mowers having replaceable power sources;

[0030]FIG. 11 is a rear elevational view showing a three-wheelelectrically-driven mower having a replaceable power source and showinga stationary stand for allowing a discharged, removable power source tobe replaced by a freshly charged power source;

[0031]FIGS. 12 and 13 show a side elevational view and a perspectiveview, respectively, of a trailerable buggy of the present invention fortransporting a power source, such as a battery, and a motor/generatorset as sources of electrical energy;

[0032]FIG. 14 shows an electrical circuit diagram for a series-parallelcombination of three battery packs, one of which is on the mower and twoof which are towed on a trailer;

[0033]FIG. 15 shows an exemplary 9-hole golf course to illustrate themethod of the present invention in strategically placing fresh batterypacks around the golf course so that discharged battery packs may bedisconnected from an electrically-driven mower and replaced with freshbattery packs.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] The present invention is directed to a riding greens mowerpowered directly by electric power or indirectly by electric powerthrough a hydraulic drive system. For the purpose of providing adetailed description of the preferred embodiments of the invention, theinvention is described as embodied as an electric or electrohydraulictriplex reel greens mower or a quintplex reel greens mower, each havinga frame supported on at least three wheels, the defined number ofreel-type lawn mowers supported from the frame member, an operatorstation including a seat from which an operator controls the function ofthe mower, and a source of electrical energy, such as on-board or towedbattery packs, a motor/generator, or a fuel cell. It should be readilyunderstood that the teachings of the present invention are not limitedto the specific type of mowers described herein and can be extended to avariety of applications in the turf care industry and elsewhere.

[0035]FIG. 1 illustrates a general arrangement of the electric turfmower 10 with an interchangeable power source 24. Mower 10 includes aframe 12 supported for movement on forward drive wheels 14 and steerablerear wheel 16. Three reel lawn mowers 18 a, 18 b and 18 c are supportedfrom frame 12 by reel lift assemblies 20 a and 20 c (the third reel liftassembly is not shown). Reel lawn mower 18 a is disposed at the leftforward corner of frame 12, reel lawn mower 18 b is disposed at theright forward corner of frame 12, and reel lawn mower 18 c issubstantially disposed below frame 12. This arrangement assures that themowers precede the ground engaging wheels such that the turfparticularly on a golf green is mowed prior to being traversed by theground engaging wheels, thereby ensuring a precise and consistent lengthof cut.

[0036] Each of the reel lawn mowers are driven by an electric reel motor111 of FIG. 2, which is supplied with electrical energy from on-boardpower source 24. Power source 24 preferably provides between 12 volts to96 volts of electrical energy. In one preferred embodiment, the powersource 24 comprises a battery pack that includes eight sixvolt lead-acidbatteries 26 connected in series to provide 48 volts of electricalenergy. As will be appreciated, a lower voltage may be used with smallerunits while a higher voltage may be used with larger units, such a fivegang fairway mower. The battery pack is replaceable and/or rechargeable,and it should be readily understood that any type of batteries, such aslead-acid or nickel cadmium (NiCad) batteries may be used with mower 10.

[0037] In another embodiment of the present invention, the electricalpower source 24 may be a fuel cell. As is well-known, a fuel cell issimilar to a battery in that it produces electricity as the result of achemical reaction. Often the chemicals reacting are merely hydrogen andoxygen. Fuel cells have a significant advantage over batteries becausethey do not run down like batteries. In this regard, as long as fuel andoxygen are supplied to the cell, it will continue to produceelectricity. Consequently, a fuel cell merely requires refueling and notrecharging. U.S. Pat. No. 5,248,566 entitled, “Fuel Cell System forTransportation Applications” discloses a fuel cell propulsion system fora wheeled vehicle, the disclosure of which is hereby incorporated byreference. Such a fuel cell system may be suitably adapted for use as apower source of the present invention.

[0038] The power source 24 also provides electrical energy to a drivemotor or primary mover (not shown in FIG. 1) which is adapted to providedriving torque through a driving axle (not shown in FIG. 1) to each ofthe forward drive wheels 14 for propelling mower 10 over the mowingsurface.

[0039] Mower 10 is operated from an operator station 30, which includesa seat 32 supported above frame 12 and power source 24 by seat support34. Operator station 30 also includes a control support arm 36 which issecured to a rearward portion of the frame 12. Control support arm 36extends forwardly and around the seat 32 such that a steering wheel 38is located directly in front of the operator and a control module 40 forhousing control elements such as control switches and indicators iswithin view and reach of the operator. Located on control support arm 36and adjacent to steering wheel 38 may be a communication panel which isoperable for displaying mowing and operating instructions to theoperator. Formed integral to frame 12 and associated with operatorstation 30 is a foot deck 44. Foot deck 44 is ergonomically angled foroperator comfort and ease of reaching the drive pedal 46, brake pedal48, and the reel mower activation switch 47. Seat 32 further may alsoinclude an assist handle 49 for assisting the operator on and off themower 10.

[0040] Mower 10 also includes a steering mechanism 50 for rotatingsteerable rear wheel 16 of mower 10. Steerable rear wheel 16 is mountedto a pair of brackets 52 secured to a U-shaped yoke member 54. U-shapedyoke member 54 includes spindle 56 which is journally supported within asleeve which is in turn secured to frame 12. Spindle 56 projectsupwardly through frame 12 allowing for a steering sprocket 58 to besecured thereto. Steering sprocket 58 has a plurality of teeth 60 formedalong its circumference for engaging a plurality of complimentary teethformed in a shaft 62 projecting from steering motor 64 secured to theframe 12. Steering motor 64 enables the projection and retraction ofshaft 62 which, through engagement of teeth 60 induces rotation ofsteering sprocket 58, thereby causes rotation of steerable rear wheel16. Steering motor 64 may be an electrically or hydraulically actuateddevice which receives control commands from an electronic (or hydraulic)controller to cause projection or retraction of shaft 62. For example,steering motor 64 may be an electric motor operating a ball screwmechanism or a self-contained hydraulic cylinder integral with shaft 62.

[0041]FIG. 2 depicts a typical configuration for the electrical drivesystem of the mower of FIG. 1 for operating the primary mover, i.e., themain drive motor. The configuration of FIG. 2 will be describedgenerally with equal reference to FIG. 1, but one skilled in the artwill readily recognize that various other configurations may be readilyadapted for operation of the turf mower. The power source is exemplifiedby battery pack 81, which includes a plurality of batteries 83 connectedin series. Electrical energy output by battery pack 81 is input to motorcontroller 85. Motor controller 85 modulates the voltage from batterypack 81 to drive motor (or primary mover) 87. Motor 87 may be any of anumber of motors known to those skilled in the art, including a DC, AC,or other electrically operated motor. Selection of a particular motor inpart dictates selection of motor controller 87. One skilled in the artwill readily recognize such design considerations. Motor 87 appliesrotational motion to output shaft 89. Output shaft 89 drives atransmission 91 which converts the mechanical energy provided by outputshaft 89 into torque for driving the left and right axles 91 a and 91 b,respectively, to cause rotation of drive wheels 14.

[0042] Motor controller 85 receives the output voltage provided bybattery pack 81 and modulates the voltage input to motor 87. In thismanner, motor controller 85 modulates the output of motor 87 bymodulating the voltage input to motor 87. Motor controller 85 operatesin conjunction with an electronic control circuit 93, which determinesthe desired mower speed and varies the output of motor 87 using acontrol signal input to motor controller 85 in order to vary the outputof motor 87. Electronic control circuit 93 receives input signalsthrough a pair of potentiometers 95 and 97 which are controlled byoperator foot pedals 99 and 101, respectively. When the operator (notshown) presses operator foot pedal 99 (the brake pedal), a change in theposition of potentiometer 95 results in a variation of the signal inputto electronic control circuit 93. Similarly, when the operator depressesoperator foot pedal 101 (the drive pedal), a change in the position ofpotentiometer 97 results in a variation of the signal input toelectronic control circuit 93. Electronic control circuit 93 determinesthe desired output of motor 87 in accordance with the input signals andgenerates a control signal to motor controller 85. Motor controller 85in turn varies the output voltage applied to motor 87 in accordance withthe received control signal.

[0043] Electronic control circuit 93 also receives input from operatorcontrol panel 103, which is analogous to the operator control panelsmentioned with respect to FIG. 1. Electronic control circuit 93 thusprovides additional control for other mower control functions. Forexample, electronic control circuit 93 may also include a lift motorcontroller 105 and a reel motor controller 107 which operate lift motor109 and reel motor 111, respectively. The electronic control circuit 93receives input from operator control panel 103 and generates controlsignals input to lift motor controller 105 and reel motor controller107. The respective controllers then generate the desired signals forcarrying out the operations indicated in accordance with input from theoperator control panel 103. Examples of such controlled functionsinclude reel mower positions (raised or lowered) and reel mower speed.Lift motor 109 and reel motor 111, in addition to receiving controlsignals from lift motor controller 105 and reel motor controller 109,receive driving electrical energy from battery pack 81.

[0044] With reference to FIGS. 1 and 3, a particularly advantageousfeature of the present invention will be described herein. In a typicalall-electric turf mower, a power source comprising a fully chargedbattery pack does not provide sufficient running time to complete therequired mowing operations in a typical day of maintenance. Presentmower configurations require two mowers to complete a single day'soperation or, in the alternative, require dividing the mowing tasks overtwo days so that the mower can do half the task in one day—berecharged—then complete the mowing tasks on the second day. The formeroption proves fairly costly and inefficient, while the latter optionresults in incomplete maintenance of the golf course over the course ofthe day. It is, thus, desirable to provide a mower in which the batterypack is interchangeable to allow for use of the mower until thebatteries substantially discharge followed by the changing of thebattery pack to a fully-charged source to enable additional use of themower. This process may be repeated over the course of the day so that asingle mower may perform the entirety of the required operations bymerely changing battery packs. One system for facilitating the removalof a battery pack in an electrically powered mower that may be utilizedin conjunction with the present invention is disclosed in detail in U.S.Pat. No. 5,9834,053, issued Aug. 10, 1999, the disclosure of which ishereby incorporated by reference.

[0045]FIGS. 1 and 3 depict a first embodiment of the present inventionin which the power source 24 engages a guided, rolling platform tofacilitate the interchange of power sources 24. Referring to FIGS. 1 and3, a roller tray assembly 80 is mounted to the frame 12 of the mower 10.The roller tray assembly includes an angled channel 82 mounted forwardof the power source 24 so that the power source 24 is seated within theangular portion of the angled channel 82. The angled channel 82 providesa forward retainer and guide for the power source 24. A second angledchannel 84 is mounted rearward of the power source 24 so that the powersource is seated within the angled portion of the angled channel 84. Theangled channel 84 both guides and retains the power source 24, and inparticular, provides a rear retainer for the power source 24. Aplurality of rollers 86 connect the angled channels 82 and 84 tofacilitate the interchange of the power source 24. The rollers 86include substantially rigid rods 88 extending between the angledchannels 82 and 84. The rods 88 journally support tubular rollers 90which rotate about rods 88 and facilitate the interchange of powersources 24. Thus, the power source 24 may be easily displacedperpendicularly to the rollers 86 so that power source 24 may be removedtoward either side of mower 10.

[0046] The power source 24, as described with respect to FIG. 1, may bea battery pack including a plurality of batteries 26 having positive andnegative terminals. The batteries 26 are connected in series to providea resultant battery voltage equal to the sum of the individual voltagesoutput by each respective battery. The batteries 26 may be also tappedintermittently by conductors 92 which terminate at one connector 94.Connector 94 includes at least one output line corresponding to eachparticular conductor 92 so that a plurality of voltages may be providedin accordance with the selective tapping of the batteries 26. Having theconductors 92 terminate in one connector 94 expedites the interchange ofthe power source 24 because the operator need only disconnect oneconnector in order to electrically disconnect the power source 24. Thepower source 24 mounts within a frame 96 which includes a plurality ofangled channels 98 interconnected to define the frame 96. In thealternative, the frame 96 may be embodied as a tray or may include aplurality of cross-members extending perpendicular to and joiningopposite angled channels 98 to impart additional supporting structure tothe frame 96.

[0047] The angled channels 82 and 84 are separated by a distancesufficient to accommodate the power source 24 and the attached frame 96,but are preferably also spaced to limit movement of the power source 24perpendicularly to the direction of angled channels 82 and 84. Angledchannels 82 and 84 include pins or keys 100 inserted in holes 102 atpreferably each end of angled channels 82 and 84 to limit movement ofpower source 24 relative to mower 10.

[0048] FIGS. 4-6 depict plan, perspective, and side elevation views of abattery change stand 110 for interchanging the power source 24 of themower 10. Referring to FIGS. 4-6, the operator arranges the mower 10 tobe adjacent to a change stand 110. The mower 10 is arranged so that thedischarged power source 112 may be moved laterally from the mower 10onto the change stand 110. The change stand 110 is a flat, T-shapedplatform. The platform includes a changing plank 114 which extends fromthe main portion of the changing stand toward the frame 12 of the mower10. The discharged power source 112 may then be moved onto the changestand 110. A winch 116 having a cable extending therefrom 118 may engagethe frame of the discharged power source 112 at two attachment points120. Operation of the winch then pulls the depleted power source 112onto the change stand 110. The winch may be electrically, mechanically,or electrohydraulically operated by a system receiving power from aninternal combustion motor 122 or even from what power may remain in thedepleted power source 112. Once the depleted power source 112 isdisplaced to the main portion 124 of change stand 110, the depletedpower source 112 is moved away from the changing plank 114 so that afully energized power source 126 may be moved to replace the depletedpower source 112 on the mower 10, thus effecting a replacement of thedepleted power source 112 with a fully energized power source 126.

[0049] The change stand 110 is preferably a rigid structure having aplurality of supporting legs 128 having sufficient strength to supportthe weight of at least two power sources. A plurality of cross-members130 preferably provide additional rigidity to the overall structure ofthe change stand 110. The change stand 110 also includes a top surface132 preferably formed of a material to facilitate sliding a power sourceand its supporting frame over the top surface 132 of the change stand110. The top surface 132 may also optionally include rollers or invertedcasters to further facilitate manipulation of the power sources. Changestand 110 also preferably includes a side guard 134 which maintains thepower sources within the top surface 132 of change stand 110.

[0050] In order to replace a depleted power source 112 with a fullyenergized power source 126, the grounds maintenance crew must firstdeliver a power source to the change stand 110. A towable trailer 140provides a vehicle to deliver the energized power source 126 to thechange stand 110. FIGS. 7 and 8 depict one embodiment of a towabletrailer 140 for dispensing a power source at the change stand 110. Thetowable trailer 140 includes a pair of wheels 142 arranged for rotatablemotion about an axle 144. Axle 144 supports a platform 146 on which acharged power source 150 rests. A pair of leafs 148 hingedly mount tothe platform 146 and hinge upwardly (shown in phantom in FIG. 8) fortransporting the towable trailer 140. Leafs 148 also hinged downwardlyinto a substantially horizontal position (shown in FIG. 8) to enabletransfer of power source 150 between the change stand 110 (of FIGS. 4-6)and the trailer platform 146. In the down position, a pair of supportlegs 152 fold downwardly to provide outboard support for leafs 148.Towable trailer 140 also includes a rear support 153 and a forwardsupport 154. Both rear and forward supports 153 and 154, respectively,may be raised and lowered by the operator in accordance with aparticular operation. For example, during transfer of power sourcesbetween the towable trailer 140 and change stand 110, supports 153 and154 are typically lowered to provide additional stability to towabletrailer 140. During transport, rear support 153 and forward support 154are typically raised to facilitate transportation of towable trailer140. Forward support 154 may be of the screw-jack type mechanismtypically employed on trailer vehicles. The screw-type jack deviceincludes a caster-type front wheel 156 which is mounted to a partiallythreaded shaft 158. Partially threaded shaft 158 engages correspondingthreads of a fixed, threaded mounting 160. Rotation of partiallythreaded shaft 158 thereby causes translation of the shaft throughthreaded mounting 160 to raise and lower the caster-type front wheel156.

[0051] In operation, the towable trailer 140 is aligned so that when theleafs 148 are placed in a lowered position, they substantially alignwith changing plank 114. After the leafs 148 are lowered, the powersource 150 may then be moved to the change stand 110. Once on the changestand 110, the power source 150, the operator positions energized powersource 150, the depleted power source on change stand 110 may then betransferred onto towable trailer 140. Thus, the energized power sourcemay be exchanged with the depleted power source so that the depletedpower source may be returned to a specific location for replenishing.

[0052] It will be understood by one skilled in the art that variousmodifications of towable trailer 140 may be made. For example, towabletrailer 140 need not include leafs 148. Transfer may be effected byaligning, for example, the rear end of towable trailer 140 with thechanging plank 114 and switchably changing power sources off the rear oftowable trailer 140. Further, it will be understood by one skilled inthe art that towable trailer 140 may also function as a mobile changestand. That is, towable trailer 140 may be disposed in various locationswhere stationary change stand 110 would otherwise be disposed. Leafs 148may then be lowered to a downward position and may function similarly tothe top surface 132 of change stand 110. In this particular embodiment,the plank may be adapted for storage on the towable trailer 140 duringtransportation and attached to the rear portion of towable trailer 140when the trailer is placed in position for power source interchange.

[0053] In a second embodiment of a trailer adapted for directinterchange, FIGS. 9 and 10 depict a trailer 170 for direct exchange ofa discharged power source 112 with a charged power source 172. Note thatlike reference numerals from FIGS. 7 and 8 will be used to referencesimilar elements in FIGS. 9 and 10. FIG. 9 depicts a rear view of themower 10 with the trailer 170 arranged to the left side of the mower andsupporting a charged power source 172 for replacing the discharged powersource 112. In operation, a temporary stand 174 is erected on a side ofthe mower 10 opposite the trailer 170. Temporary stand 174 includes apair of legs 176 which support the combined weight of the stand 174 andthe power source disposed thereon. The discharged power source 112 isremoved from the mower 10 by sliding it toward the right of the moweronto temporary stand 174. Once discharged power source 112 has beenpositioned on temporary stand 174, charged power source 172 may then bemoved from the trailer 170 onto the mower 10. The trailer 170 is thenpositioned adjacent temporary stand 174 which supports discharged powersource 112. The discharged power source 112 is then transferred from thetemporary stand 174 onto the trailer 170.

[0054]FIG. 10 depicts the trailer 170 having mounted thereon a chargedpower source 172 and the temporary stand 174. The temporary stand 174 ismounted towards the rear of the trailer 170 to facilitate transportationof the trailer 170. Also shown in FIG. 10 is a ball hitch. The hitchportion 178 of a ball hitch engages a ball affixed to a towing vehiclefor transporting the trailer 170. It will be understood by one skilledin the art that the stationary and trailerable stands and trailersdepicted in FIGS. 4-10 have several features, many of which may beinterchangeable to vary the particular configuration in accordance withthe specific needs of the user. For example, the stand depicted in FIGS.4-6 may be adapted for implementation on a trailer, as discussed withrespect to FIGS. 7 and 8. In this manner, the stand need not necessarilybe fixed to achieve the same functionality, which provides the golfcourse operator flexibility in placing the change stands to maximize theuse of the interchangeable power sources.

[0055]FIG. 11 depicts yet another embodiment of a turf mower 190 havingan interchangeable power source, such as battery pack 192. The mower 190also includes an alternative configuration for the steering mechanism196 for rotating steerable rear wheel 198 of mower 190. Steerable rearwheel 198 is mounted to a pair of brackets 200 secured to a U-shapedyoke member 202. U-shaped yoke member 202 includes a spindle 204journally supported within a sleeve 206 secured to the frame 208. Thespindle 204 projects through a steering sprocket 210. Steering sprocket210 has a plurality of teeth 212 formed along its circumference forengaging a plurality of complimentary teeth 214 formed in an input gear216. The input gear 216 is driven by a motor 218 which is attached to adownwardly extending motor support 220 which extends from the frame 208.Locating the steering mechanism 196 entirely beneath the frame 208provides an added advantage through reducing the size of the rearportion of the mower 190.

[0056] The battery pack 192 is disposed within a rack 230. The rack 230has a lower platform 232 which supports the individual batteries 234. Anupper rail 236 of the rack 230 provides upper stability to theindividual batteries 234 of the battery pack 192. Disposed beneath thelower platform 232 are a plurality of rollers 238 attached to the lowerplatform 232. The rollers 238 facilitate movement of the battery pack192 over the top surface of frame 208. Further, the mower 190 includeson either side of the frame 208, where the battery pack 192 is located,gates 240 which retained the battery pack 192 laterally on the mower190. The gates 240 may be lowered to enable the transfer of a batterypack onto and off of the mower 190.

[0057]FIG. 11 also depicts the battery change rack 260 which enable theinterchange of battery packs onto and off of mower 190. Battery changerack 260 preferably rests on a substantially stable foundation 262, suchas cement or concrete. Also, the foundation 262 supporting batterychange rack 260 is also preferably of a size sufficient to accommodatethe mower 190 during a battery change. Foundation 262 also preferablyincludes a recessed portion 264 which receives the battery change rack260. The battery change rack 260 is then secured to the foundation 262using fasteners 266 which project through tabs 268 located on the sidesof battery change rack 260. Battery change rack 260 includes a pair ofshelves 270 and 272 which received the battery packs (as shown withbattery pack 192′ on shelf 270). The shelves are rigidly connected withvertical members 274 which provide sufficient separation between uppershelf 270 and lower shelf 272 to accommodate a battery pack 192. Anupper horizontal track 276 attaches to the lower portion of lower shelf272. Upper horizontal track 276 accommodates a pair of rollers 278 whichdefine the upper portion of a scissor jack 280 and enables translationof the rollers 278 within the horizontal track 276 in accordance withthe raising and lowering of scissor jack 280. Thus, turning of the crank282 results in the corresponding raising or lowering of the upper shelf270 and lower shelf 272 of battery change rack 260.

[0058] The lower portion of scissor jack 280 includes a pair of rollers284 which translate within lower horizontal track 286. Similarly, a pairof vertical tracks 288 accommodate rollers 290 which translate withinthe track 288. The rollers 290 are attached to the upper shelf 270 andlower shelf 272 so that the upper and lower shelves remain horizontallystable during the raising and lowering operation.

[0059] In operation, the operator positions the mower 190 adjacent tothe battery change rack 260. One of the upper shelf 270 or lower shelf272 preferably does not contain a battery pack. The empty shelf is thenpositioned in substantial vertical alignment with the upper surface ofbattery frame 208. The operator then transfers the battery pack 192 fromthe mower 190 onto the empty shelf (272 as shown in FIG. 11). Theoperator then turns the crank 282 to align the charged battery pack 192′with the top surface of the frame 208. Once the frame and the top shelf270 are vertically aligned, the operator then moves the battery pack192′ onto the battery frame 208 to complete the interchange of adischarged battery pack 192 with a charged battery pack 192′. It will beunderstood by one skilled in the art that various modifications of thepresent invention may be implemented in the embodiment of FIG. 11. Forexample, scissor jack 280 may be any of a number of devices whichmechanically assist in the raising and lowering of the battery packs,including various electric, hydraulic, and other mechanical devices.Further, the roller structure for the battery frame may be any of anumber of known friction reducing devices which facilitate moving thebattery packs.

[0060]FIG. 12 depicts yet another embodiment of the present invention inwhich a turf mower 300 is adapted to tow a trailer 302 which providesthe electrical energy for driving the mower 300. The mower 300 issubstantially similar to the mowers described with respect to FIGS. 1-11but further includes a tow bar 304 having a ball 305 adapted to engage ahitch 306 attached to trailer 302. An electrical conductor 308 providesan electrical connection between the mower 300 and the trailer 302. Theconductors 308 a and 308 b pass through anchors 310 and 312 to maintainthe conductors 308 a and 308 b in a substantially fixed position. Suchrouting enables movement between the mower 300 and the trailer 302 whilelimiting flexing of the electrical conductors 308 a and 308b. Aconnector 314 joins conductors 308 a and 308 b and enables for quickinterconnection between conductors 308 a and 308 b so that the trailermay be easily separated from the mower 300.

[0061] In a first configuration of the present embodiment, the trailer302 includes a pair of wheels 316 supporting the main platform 318. Ascrew jack 320 having a crank handle 322 may be operated to support thetrailer 302 when disengaged from the mower 300. Following engagement ofthe tow bar 304 with the hitch 306, the screw jack 320 may be raised tolower the hitch 306 onto the ball 305 to enable transport of the trailer302. A battery pack 324 includes a plurality of batteries 326 housed ina frame 328 which rests on main platform 318. The batteries may beinterchanged using one of the methods described herein. The battery pack324 is placed on a lower shelf 330 of main platform 318. Amotor/generator set 334 rests upon the top shelf 332 of the trailer 302.The motor/generator set 334 includes an internal combustion motor 336which provides mechanical input to one of a motor or generator 338converts the mechanical input energy into electrical energy to drive themower 300. The internal combustion motor 336 receives fuel from a fuelsource such as a fuel tank 340 and preferably includes a muffler toabate noise generated by the internal combustion motor 336. Themotor/generator set 334 also includes a gel cell 342 to provideelectrical input for starting the internal combustion motor 336. Themotor/generator set 334 operates in conjunction with battery pack 324 toprovide driving electrical energy to the mower 300. Further, themotor/generator set 334 preferably provides sufficient electrical energyto charge battery pack 324 when the electrical output of the batterypack 324 drops below a predetermined level.

[0062] In another embodiment of the present invention, a second batterypack 324 may substitute for the motor/generator set 334 on the top shelf332 of the trailer 302. A dual battery pack configuration has particularappeal when operating in golf courses in residential areas which requireextremely low noise levels. Thus, the all electric mower 300 driven bydual battery packs 324 presents a particularly quiet option foroperation of the mower 300. The trailer 302 may also include a ventedcover 344 to prevent dirt, moisture, and other debris from entering theinterior of the trailer 302.

[0063] In yet another embodiment, the ball 305 and the hitch 306 alsoconnect electrically to indicate a positive connection therebetween. Inthis manner, the ball 305 and hitch 306 cooperate so that a goodmechanical connection must be established prior to establishment of anelectrical connection. The electrical connection may then be checkedprior to enabling operation of the mower 300. This provides anelectrical interlock mechanism to allow for safe operation of the mower.

[0064]FIG. 13 depicts the mower 300 of FIG. 12 towing the trailer 302 ofFIG. 12. In yet another embodiment of the present invention, a secondtrailer 350 which may be configured in accordance with either of theembodiments described with respect to FIG. 12. Multiple trailers couldbe joined to further increase the store of electrical energy potentialof the mower 300. Each trailer must include a forward hitch 352 and arear tow bar 354 for attachment to the forward hitch 352 of thefollowing trailer. FIG. 13 also depicts two alternative configurationsfor the covers of the trailers 302 and 350. Trailer 302 includes avented cover 344 having perforations 356 in the top surface of thevented cover 344. Trailer 350, on the other hand depicts a cover 358having a peaked roof 360 and a vent 362 extending along the peak.

[0065] In still another embodiment of the present invention, amotor/generator set similar to that shown at 334 in FIG. 12 may bemodularly interchangeable with power source 24 as shown in the mower 10of FIG. 1. Interchange of these electrical supply components may beaccomplished using any of the methods as described herein.

[0066] It should be noted by one skilled in the art that the trailers ofFIGS. 7-10 may be adapted to operate in multiple trailer configurationsas described above so that an individual towing vehicle can dispense aplurality of battery packs or be deposited at predetermined locationsthroughout the course for interchange with discharged batteries from themowers.

[0067]FIG. 14 depicts a wiring schematic for providing electrical energyto a mower 370 from a battery cart 372 having a first battery pack 376and a second battery pack 374. In addition, mower 370 also includes abattery pack 378. A plurality of battery taps A1, B1, and C1 connect tothe negative terminals of batteries 374, 376 and 378, respectively.Similarly, a plurality of battery taps A2, B2, and C2 connect to thepositive terminals of battery packs 374, 376, and 378, respectively.Battery taps A1, B1, and C1 terminate at the end opposite the negativeterminal at an output pin 382 of a connector 384. Similarly, the endopposite the positive terminals of taps A2, B2, and C2 terminate at anoutput pin 386 of connector 384. Intermediate voltages between thenegative and positive terminals may also be obtained by providing abattery tap between intermediate batteries 380 of the respective batterypacks 374, 376, and 378. For example, assuming that each battery outputs8 volts, battery taps A4, B4, and C4 connect so as to provide a 24 voltpotential between taps A4, B4, and C4 and taps A1, B1, and C1,respectively. The battery taps A4, B4, and C4 terminate at the outputpin 388 of connector 384. Other intermediate output voltages may besimilarly obtained using battery taps A4-6, B4-6, and C4-6.

[0068] Each battery tray 374, 376, and 378 includes a single conductorhaving two terminal connections A7 and A8 and B7 and B8 and C7 and C8,respectively. The single conductors enable the controller to verify apositive electrical connection between connector 384 and a matingconnector. By verifying a current flow or voltage potential across eachconnector pair A7 and A8, A7 and A8, and A7 and A8, the system canverify an electrical connection between connector 384 and a matingconnector to help ensure safe operation of the vehicle. It should benoted that while the embodiment of FIG. 14 is primarily directed to aconfiguration similar to FIG. 12 wherein two battery packs are providedon the battery trailer, such interconnection method may be equallyapplicable to the above-discussed embodiments depicting a mower carryinga single interchangeable battery.

[0069] In operation, when mowing around the golf course, and inparticular the fairways, a towed battery trailer arrangement asdescribed in FIGS. 7-13 enables disbursement of the replacement batterypacks about predetermined battery drop sites. The operation to bedescribed herein refers particularly to the embodiment of FIG. 12 (withbattery packs in each trailer). The operation generally begins withdisbursing the replacement battery packs at predetermined battery dropsites. Prior to disbursing the replacement battery packs at thepredetermined drop sites, the operator first attaches to the mower, or asuitable towing vehicle, as will be understood by one skilled in theart, a predetermined number of towable battery trailers. The operatorengages the first trailer to the battery hitch provided at the rear ofthe electric mower or suitable towable vehicle. To the rear of the firstbattery trailer, a second towable battery trailer having additionalreplacement battery packs is attached to the rear of the first trailerby means of a hitch. Of course, it will be understood by one skilled inthe art that this arrangement may be further repeated in accordance withthe number of trailers to be dispatched to predetermined drop sitesabout the golf course.

[0070] Referring the FIG. 15, which depicts an exemplary layout of anine hole golf course, the operator departs the service building andproceeds around a predetermined path, indicated by the dotted line ofFIG. 15, to disburse a first replacement battery at battery drop siteone near the tee area of the seventh hole. At battery drop site one, theoperator disengages the second towed trailer and lowers the front pad orwheel to provide a third supporting member to supplement the supportprovided by the ground engaging wheels. The operator next proceeds alongthe predetermined path, as indicated by the dotted lines, to batterydrop site two, near the pin area of the third hole. Similarly asoccurred at battery drop site two, the operator disengages the towabletrailer at battery drop site two and lowers the third support member,which again may be either a support pad or a lockable wheel, to providea third support member for the towable trailer disposed at battery dropsite two. After dispatching the replacement battery packs at drop sitetwo, the operator then proceeds to mow the fairways in the specifiedorder of the first, second, and third holes.

[0071] Following the completion of mowing at the third hole, theoperator proceeds to battery drop site two where the battery pack on themower, which is in a discharged state, is replaced with a fresh, fullycharged battery pack from the trailer dispatch to battery drop site two.Upon replacement of the discharged battery with a fully charged batterypack, the operator then proceeds to mow fairways four, five, and six.After mowing the sixth fairway, the operator proceeds to battery dropsite one where the battery pack installed at battery drop site two,which will now be in a discharged state, is replaced with a fullycharged battery pack found at battery drop site one. The operator thenproceeds to mow the fairways of the seventh, eighth, and ninth holes.After completion of the ninth hole, the operator then proceeds to theservice building.

[0072] Alternatively, after completion of mowing the ninth hole, theoperator may then proceed along the predetermined path, indicated by adotted line, to battery drop site two where the towable trailer found atbattery drop site two is attached to the trailer hitch found at the rearof the mower. The operator then proceeds to move the mower and theattached battery trailer to battery drop site one where the trailerfound at battery drop site one is hitched to the trailer hitch found atthe rear of the towable trailer hitch to the fairway mower at batterydrop site one. The operator then tows both towable battery trailers backto the service building where all three battery packs, which are in acurrently discharged state, can be recharged in anticipation of the nextday's operation. Of course, it will be understood by one skilled in theart that the following procedure may vary in accordance with the mowingto occur, the discharge rate of the batteries, the number of holes onthe golf course, and the length of the holes on the golf course, as wellas several other factors. The above description is primarily anexemplary description of one particular implementation of theabove-described operation.

[0073] The foregoing detailed description shows that the preferredembodiments of the present invention are well suited to fulfill theobjects above-stated. It is recognized that those skilled in the art maymake various modifications or additions to the preferred embodimentschosen to illustrate the present invention without departing from thespirit and proper scope of the invention. For example, drive motors,reel motors, lift motors and steering motors of different voltages maybe utilized, and the taps into the battery packs may be changedaccordingly. Further, gear boxes may be used between the reels and reelmotors if desired, and the number of batteries in the battery pack maybe varied as needed.

[0074] While the present invention has been discussed with respect toriding mowers having a reel-type mowing heads, those skilled in the artwill appreciate that it may be applied to electrically-powered ridingmowers having multiple rotary mowing heads. In addition, the electricalcontrol systems, generator set arrangements, and virtually all otheraspects of the present invention may be used in connection with otherturf care equipment used to tend large expanses of grass. For example,electrically-powered riding sprayers, aerators, dethatchers, and otherequipment which would be beneficially operated in a pollution-free waywith extremely low noise would benefit by the systems and structures ofthe present invention. In other words, except for the working tool beinga mowing head, most such equipment can be readily adapted to utilize thevarious aspects of the present invention. Thus, the term “turf caremachine” or “turf care equipment” if used in the claims below is to beunderstood to extend to all such forms of power-consuming equipment whenarranged to be operated and/or driven using electrical motors and/orelectrically-powered work-producing devices. Accordingly, it is to beunderstood that the protection sought and to be afforded hereby shouldbe deemed to extend to the subject matter as defined by the appendedclaims, including all fair equivalents thereof.

What is claimed is:
 1. A self-propelled riding mower comprising: a framesupported upon a plurality of ground engaging wheels; a first electricalpower source; a plurality of mowers supported from said frame, saidmowers being moveable between a raised non-operative position and alowered operative position, said mowers being driven by electric motorsreceiving electrical power from said first electrical power source; aprime mover comprising an electric motor supplied with electrical energyfrom said first electrical power source and adapted to provide drivingtorque to at least one of said ground engaging wheels; a secondelectrical power source; and a trailer including a platform supportedupon a plurality of ground engaging wheels for carrying said secondelectrical power source behind said frame, said trailer interconnectedto said frame by a hitch.
 2. The self-propelled riding mower of claim 1further comprising: an electrical connection between said firstelectrical power source and a control circuit; and an electricalconnection between said second electrical power source and said controlcircuit.
 3. The self-propelled riding mower of claim 1 furthercomprising; a support for said first electrical power source on saidmower, engaging and disengaging said frame to facilitate removal andinstallation of at least a portion of said first electrical powersource.
 4. The self-propelled riding mower of claim 1 wherein saidsupport further comprises a tray supporting said power source and aguide fixed to said frame, where said tray engages said guide to alignsaid tray and to facilitate removal and installation of said tray. 5.The self-propelled riding mower of claim 1 wherein said frame furthercomprises friction reducing means disposed beneath said support suchthat said support engages said friction reducing means duringinstallation onto and removal from said frame.
 6. The self-propelledriding mower of claim 1 wherein said first electrical power sourcecomprises a battery power source.
 7. The self-propelled riding mower ofclaim 1 wherein said first electrical power source comprises amotor/generator set.
 8. The self-propelled riding mower of claim 1wherein said first electrical power source comprises a fuel cell.
 9. Theself-propelled riding mower of claim 1 wherein said second electricalpower source comprises a battery power source.
 10. The self-propelledriding mower of claim 1 wherein said second electrical power sourcecomprises a motor/generator set.
 11. The self-propelled riding mower ofclaim 1 wherein said second electrical power source comprises a fuelcell.
 12. The self-propelled riding mower of claim 1 wherein said secondelectrical power source comprises a battery power source and amotor/generator set.
 13. The self-propelled riding mower of claim 12wherein said motor/generator set and said battery power source arevertically arranged, one on top of the other.